Dairy nutrition often focuses on what goes into the ration, energy, protein and minerals, balanced to meet the cow’s requirements. However, on-farm, what is formulated and what the cow actually receives are not always the same.
In both total mixed ration (TMR) and grazing systems, variation in intake, feeding patterns and rumen conditions means nutrient supply is inherently inconsistent. In grazing systems, where pasture quality and intake can change daily, this variability is even more pronounced.
The result is a gap between diet formulation and nutrient delivery, which can limit performance, reduce efficiency, and increase the risk of metabolic malfunction.
Why nutrient delivery varies
In both TMR and grazing systems, cows experience variation in nutrient supply across the day. However, grazing systems typically amplify this variability due to pasture growth dynamics, changing sward structure, and variable intake behaviour between animals.
In pasture-based systems, intake is less controlled and often occurs in distinct grazing bouts. Supplementation is typically delivered in discrete feeding events, meaning cows experience peaks and troughs of nutrient intake rather than a steady supply we refer to this as “slug feeding”.
This leads to fluctuations in rumen fermentation and nutrient availability.
Research has shown that rumen pH can vary substantially throughout the day, with cows often spending several hours below pH 5.8, a level associated with subacute ruminal acidosis.
Another example is that when nutrients arrive at different times, microbial efficiency declines, and excess nitrogen is converted to urea rather than being captured as microbial protein.
This variability has direct consequences whereby only 20–30 per cent of dietary nitrogen is typically captured in milk, with the remainder lost via urine and faeces.
To be efficient, rumen microbes rely on a stable supply of fermentable energy and rumen degradable protein (RDP) for the synthesis of microbial protein, necessary for milk protein synthesis and muscle growth.
If variability in intake cannot be eliminated, particularly in grazing systems, the next step is to improve how nutrients are delivered within the cow.
When natural supply is not enough: B vitamins as an example
Although rumen microbes produce many B vitamins, this supply is not constant. It depends on rumen conditions such as pH and substrate availability, which fluctuate throughout the day.
Under high production or metabolic stress, microbial supply may not always meet demand. Research has shown that supplementation with protected forms of B vitamins such as folic acid and vitamin B12 can improve milk production, reproduction, and metabolic status.
These responses are driven not just by increased supply, but by more reliable delivery to the site of absorption in the small intestine.
From precision to reliability
Dairy nutrition has made major progress in defining requirements and improving ration formulation. However, further gains are increasingly limited by biological variability rather than formulation accuracy.
The next step is not simply greater precision in what is fed, but greater reliability in how nutrients are delivered and utilised within the cow.
This means shifting from:
- balanced diet → delivery of nutrients at the right time and rate
- average intake → nutrient supply over time
- correct formulation → nutrients reaching the right place and usable
Microencapsulation fits within this shift by helping protect nutrients and control their release, improving consistency of delivery under real farm conditions.
Closing the gap
In both grazing and TMR systems, variability in nutrient delivery is unavoidable, more so in grazing systems.
It is clear that inconsistency reduces efficiency, affecting rumen stability, nutrient utilisation, and metabolic resilience.
Technologies such as microencapsulation help address this by improving the consistency of nutrient delivery. In doing so, they support a more reliable link between what is fed and what the cow actually receives. Ultimately, improving performance depends on feeding more precisely and consistently.
Jefo Nutrition manufactures rumen-protected solutions designed to support consistent and efficient delivery of nutrients to dairy cows. For more information, contact your nutritionist or Jefo representative.